Heretofore, there have been proposals on a process for producing a polybutene-1 polymer having a high crystal property. However, most of them use a titanium trichloride as a catalyst to conduct a solution polymerization and a slurry polymerization. On the other hand, it is foreseen that if a butene-1 polymer could be produced by means of a vapor phase polymerization, the process would be simplified and production costs would be reduced. Because of this reason, there have been proposals which suggest possibilities of a vapor phase polymerization of a butene-1. However, there remained various problems yet to be solved in order to put into practice the process according to this kind of proposals in an industrial scale.
For example, a butene-1 polymer, when compared with polyethylene and polypropylene, has a strong affinity for a hydrocarbon solvent. Accordingly, if a small amount of solvent should be accompanied when a catalyst component is supplied to a vapor phase polymerization system, polymers would be more easy to coagulate each other. As a result, it becomes difficult to effect a stable operation for a long period or to actuate the apparatus.
When a vapor phase polymerization is carried out using a catalyst of a titanium trichloride catalyst (see JP-A-192716/85) conventionally often used, a catalyst of a magnesium chloride catalyst (see JA-A-6205/84) and the like, the catalytic activity becomes weak, a stereoregularity of the butene-1 polymer obtained is insufficient and the advantage resulting from the use of the vapor phase polymerization method is not sufficiently enjoyed.